One known type of information storage device is a disk drive device that uses magnetic media to store data and a movable read/write head that is positioned over the magnetic media to selectively read from or write to the rotating magnetic media, such as a magnetic disk.
FIG. 1a illustrates a conventional disk drive device 200 and shows a magnetic disk 101 mounted on a spindle motor 102 for spinning the disk 101. A voice coil motor arm 104 carries a head gimbal assembly (HGA) 100 that includes a micro-actuator 105 and a slider 103 incorporating a read/write head. A voice-coil motor (VCM) is provided for controlling the motion of the motor arm 104 and, in turn, controlling the slider 103 to move from track to track across the surface of the disk 101, thereby enabling the read/write head to read data from or write data to the disk 101. In operation, a lift force is generated by the aerodynamic interaction between the slider 103 and the spinning magnetic disk 101. The lift force is opposed by equal and opposite spring forces applied by a suspension of the HGA 100 such that a predetermined flying height above the surface of the spinning disk 101 is maintained over a full radial stroke of the motor arm 104.
FIG. 1b illustrates a perspective view of the slider shown in FIG. 1a in a bottom view. As illustrated, a magnetic reading/writing head 116, which is used for realizing data reading/writing operation of the slider relative to the disk 101, is formed on one side surface of the slider 103. The slider 103 has an air bearing surface (ABS) 117 facing to the disk 101. When the disk drive device is in operation, an aerodynamic interaction is generated between the ABS 117 of the slider 103 and the rotary disk 101 in a high speed, thus making the slider 103 floating over the disk 101 dynamically to perform data reading/writing operation.
To make the slider read data from or write data to the disk successfully, the slider is required to have a good flying stability, i.e. the flying height of slider is kept at an invariable value when the slider is flying over the disk. If the slider has a bad flying stability, the flying height is variable i.e. sometimes the flying height becomes higher and sometimes the flying height becomes lower. If the flying height is too high, the slider may not successfully realizing a read/write operation; if the flying height is too low, the slider may scratch the disk to cause a damage of the disk and/or the slider.
Understandably, manufacturing accuracy of the ABS of the slider is a key factor to influence the flying stability of the slider. Here, a process of forming the ABS of the slider is described briefly as follows. Generally, the ABS of the slider is formed by photolithography process and vacuum etching process in sequence. At first, a photo-resist coating is covered on an ABS-forming surface of the slider; then, an air bearing surface pattern (ABS pattern) are transferred to the photo-resist coating by exposure; next, the photo-resist coating is developed to get rid of unexposed portions of the photo-resist coating; and finally, portions of the ABS-forming surface uncovered by the photo-resist coating is etched by ion beam to form an ABS.
In related art, a manufacturing process of the slider is typically based on a plurality of slider row bars, each of which is constructed by a plurality of slider bodies. A slider row bar may comprise 30-100 slider bodies according to different product type. These slider row bars are encapsulated together by adhesive to form an entire row bar assembly. After being processed, these row bar assemblies are separated from each other and finally each of these row bar assemblies is cut into separate sliders.
FIGS. 2a-2b show a slider row bar used for forming sliders. As shown in the figures, the slider row bar 2 has a width W and a thickness T. The slider row bar 2 has an ABS-forming surface 3. FIG. 2c shows a carrier 1 for holding the slider row bars 2. The conventional slider row bar bonding method is preformed as follows: firstly, as shown in FIG. 3, a kind of fast-curing glue 5 is dispensed on the carrier 1 by a glue dispenser 6. Then, as shown in FIG. 4, a slider row bar 2 is moved toward the carrier 1 by a vacuum pickup head 7 and then adhered to the carrier 1 by the fast-curing glue 5. Here, the slider row bar 2 has a slider-mounting surface 4 to contact the fast-curing glue 5, which is opposite to the ABS-forming surface 3. Next, as shown in FIG. 5, the above two steps are repeated until all the slider row bars 2 are attached on the carrier 1, and then, the row bars are kept for 1-3 hours so that the glue 5 is cured completely so that all the slider row bars 2 are fixed on the carrier 1. Then, as shown in FIG. 6, a kind of encapsulating glue 9 is dispensed in the gaps formed between the slider row bars 2 by a glue dispenser 8. Finally, the encapsulating glue 9 is exposed to ultraviolet light and eventually cured to bond all the slider row bars 2 together to form a slider row bar assembly.
FIG. 7a shows a plurality of slider row bars 2 encapsulated together and bonded onto the carrier 1. FIG. 7b shows a cross-sectional view of FIG. 7a taken along line Z-Z. Referring to FIG. 7b, a plurality of glue recesses 30 are formed in a plurality of gaps (not labeled) between the slider row bars 2. The glue recesses 30 are formed by natural shrinkage of the encapsulating glue 9 during curing process. Referring to FIG. 7a and FIG. 7b, the ABS-forming surfaces 3 of the slider row bars 2 and the glue recesses 30 form a base surface of the slider row bar assembly on which a photo-resist coating will be covered.
Also referring to FIG. 7b, it is easily to understand that the flatness of the base surface of the slider row bar assembly is mainly determined by two factors: the glue recesses 30 and thickness uniformity of the slider row bars 2. First, as the slider row bars 2 have a small thickness, normally in a range of hundreds of microns, it is very difficult to improve thickness uniformity of the slider row bars 2. On the other hand, the glue recesses 30 are unavoidable due to the inherent character of the encapsulating glue 9. In the conventional slider row bar bonding process, because each of the slider row bars 2 and the glue 5 thereunder has a different thickness (i.e. the slider row bars 2 and the glue 5 thereunder has a thickness variation), and there are the glue recesses 30, the flatness of the base surface of the slider row bar assembly is decreased seriously. Accordingly, a photo-resist coating formed on the base surface of the slider row bar assembly has a bad flatness.
In the photolithography process of forming the ABS of the slider, the flatness of the photo-resist coating has a big influence on manufacturing accuracy of the ABS of the slider. More concretely, if the flatness of the photo-resist coating covered on the ABS-forming surfaces is bad, the ABS patterns transferred to the photo-resist coating through exposure will have a distortion in shape relative to the predetermined ABS pattern. Accordingly, the ABS pattern formed on the slider row bars by etching process will not match the predetermined ABS pattern. This will make the slider with such a ABS pattern have a bad flying stability and thus make the disk drive has a bad flying performance and may has a fear that the disk and/or the slider may be damaged.
Thus, it is desired to provide a method for bonding slider row bars for photolithography process to overcome the above-mentioned drawbacks.